The requirement of the inwardly and upwardly directed portion of the roof structure for adequate car clearance will be readily appreciated upon an understanding of the section entitled "Fundamentals for Design Fabrication and Construction of Freight Cars" in CAR AND LOCOMOTIVE CYCLOPEDIA, id., p. S2-1 to S2-10. For purposes of interchange of rail cars between different rail lines in the United States, the clearance standards explained in the cited material must be uniformly observed as design parameters. Accordingly, in order to maximize the height of an automobile transit rail car to the point where three auto hauling decks may be utilized while still meeting the clearance diagrams promulgated and adopted for interchange cars by the Association of American Railroads, it is necessary to provide an inwardly and upwardly directed roof portion.
A particular design problem has been encountered because of the necessity of an inwardly and upwardly directed roof structure and multi-decked automobile transit rail cars in that the straight vertical multiple panels of folding doors, if upwardly extended sufficiently to substantially close the interior cavity in the region of the upper deck, will not be capable of inward movement to the position of storage along the inside rail car wall upon being pivotally folded back upon each other to the open position. The new multiple panel folding door combinations of the instant invention provides substantially complete closing of the car end opening and yet solve this storage problem.